Phosphates are mostly found
on places where organic materials have decomposed, for example remains
of meat or fish in settlements. The phosphates are insolutible in water
and generally stay where they are disposed. Still, it can happen that
they are transported with water.

An amount of soil (minimum 0,5l) is taken from the
relevant sampling spot, and the location is marked with coordinates. The
phosphates are separated with acid. High amount of organic material disposed
on the spot will give a high amount of phosphates.

The density of samplingspots will form the basis of
how detailled the result will be. While stone age settlements often have
high and uneven values, iron age settlements often have uneven values,
and the samples here must have higher density. Graves can be investigated
in detail by dense sampling, and in some cases it is possible to determine
where the body has been placed.

In Sundfjaera we aimed to collect samples every 10th
meter in the area being excavated. Inside the dwellings samples were collected
every 2nd meter. In mounds, cooking pits, firespots etc. the samples were
collected denser and from profiles.